Abstract:
This research was done to determine the antimicrobial activity of castor oil plant parts (seed and leaves) on spoilage microorganisms of plantain fruits and vis-a-vis standard
antibiotics. Plantain fruits were subjected to spoilage for 7days.The spoilage bacteria were characterized and identified using conventional and modern methods. The organisms isolated include: Corynabacterium sp., Staphylococus aureus and Proteus vulgaris. Castor oil plant (Ricinus communis) leaf and seed were extracted using ethanol and water. The phytochemical analysis of plant extracts were also carried out. The antimicrobial activities of the ethanol and aqueous extracts were tested on the isolates at different concentrations (100mg/ml, 150mg/ml, 200mg/ml and 250mg/ml). The extracts were effective on the bacterial isolates with range of Minimum inhibitory concentration (MIC) values from 25.0mg/ml -100.0mg/ml, Staphylococcus aureus at 12.5mg/ml – 100mg/ml and Proteus vulgaris at 50mg/ml- 100mg/ml. The aqueous extracts of the leaf inhibited Corynabacterium sp., and Staphylococcus aureus but it did not inhibit Proteus vulgaris. Proteus vulgaris was also not inhibited by the aqueous seed extract, Corynabacterium sp. and Staphylococcus aureus were inhibited only at higher concentrations. Antibiotic susceptibility test showed that Corynabacterium sp., was inhibited more by the ethanolic seed extract than it was inhibited by Amoxicillin at the same concentration of 250mg/ml.
